Method And A System For Visual Human-Machine Interaction

ABSTRACT

A method for visual interaction between a user ( 10 ) and a machine ( 20 ) using gaze estimation is disclosed. The method comprises: displaying an initial element and one or more further elements on a display ( 30 ), each further element being spatially separated from the initial element, whereby each further element defines an angular range with respect to the position of the initial element; determining that a direction from a first gaze point to a second gaze point lies within the angular range defined by a further element selected by the user; and sending instructions to the machine to perform a function associated with the selected element. A system ( 1 ) for visual interaction between a user ( 10 ) and a machine ( 20 ) using gaze estimation is also disclosed. The gaze points of the user may be determined with relatively low precision.

TECHNICAL FIELD

The present invention relates to a method and a system for visualinteraction between a user and a machine.

BACKGROUND OF THE INVENTION

Eye tracking techniques enable human-machine interaction through eyegaze. These techniques may for example be used for inputting text into acomputer. In such applications, a user usually “types” by firstselecting a letter by gazing at an icon of the letter shown on a screen.The gazed-upon icon is highlighted, and the user finally confirms theselection by for example blinking or letting his or her gaze dwellbriefly on the highlighted icon. A discussion of gaze-controlled textinput can be found in the paper “Gazing with pEYEs: towards a universalinput for various applications” (by A. Huckauf and M. H. Urbina andpublished in “Proceedings of the 2008 symposium on Eye tracking research& applications”, ETRA '08, pages 51-54, ACM, New York, N.Y., USA).

Text input and other applications where a user interacts with agraphical interface shown on a display through eye gaze typicallyrequire the gaze direction to be determined with high precision. Highprecision usually requires accurate calibration of the eye trackingsystem with respect to eye parameters and glint parameters, somethingwhich drives cost due to requirements on illumination for glintgeneration and camera resolution. In addition, the calibration procedurenormally involves a series of measurements in which the user must lookcarefully at a sequence of different targets. The procedure istime-consuming and perceived as complicated by many users.

A system which reduces the need for accurate calibration is disclosed inU.S. 2014/0354539. As disclosed therein, a user selects an inputoperation to an operating system by following a moving graphical controlon a screen with his or her gaze. The input operation associated with aparticular graphical control is selected if the movement of the gazematches the movement of the graphical control. Although the need foraccurate calibration is reduced in the system disclosed in U.S.2014/0354539, the system is rather complicated, for example because ofthe requirement of several interaction modes (unidirectional andbidirectional). Moreover, some users may find it difficult orinconvenient to follow the moving graphical controls with their gaze,and the process of selecting an operation is also rather slow.

SUMMARY OF THE INVENTION

In view of the foregoing, there is a perceived need for an improved oralternative method for visual human-machine interaction.

To address this need, there is presented, according to a first aspect ofthe invention, a method for visual interaction between a user and amachine using gaze estimation, wherein the method comprises activatingan interaction mode, and wherein the interaction mode comprises thesteps of: displaying an initial element on a display, the initialelement having a fixed position; estimating a first gaze point of theuser; assuming that the user is gazing at the initial element;displaying one or more further elements on the display, each furtherelement being associated with one or more functions of the machine andhaving a fixed position spatially separated from the position of theinitial element, whereby each further element defines an angular rangewith respect to the position of the initial element; estimating a secondgaze point of the user; determining that a direction from the first gazepoint to the second gaze point lies within the angular range defined bya selected further element of the one or more further elements; andsending instructions to the machine to perform at least one of the oneor more functions associated with the selected element.

Current eye tracking systems are usually capable of determining relativedirections with good accuracy even with no, or only approximate, initialcalibration because of error cancellations. The invention is based onthe realization that it is not necessary to use moving graphical userinterface elements to exploit this property. In the present invention,the graphical user interface elements do not move on the screen as inthe system disclosed in U.S. 2014/0354539. Instead, the user selects afunction via the movement of his or her gaze relative to one of thegraphical user interface elements (i.e. the “initial element”). Theresult is a method for visual human-machine interaction which is simpleto implement and which enable fast interaction with a small risk of userselection errors because of its ease of use.

Moreover, since no or only low-precision calibration of the eye trackingsystem is required, the requirements on, for example, camera resolutionand glint generation are relatively low, something which helps to reducecosts. As an example, calibration with respect to glint parametersand/or visual axes parameters is usually not required.

The activating step may comprise at least one of the steps: determiningthat a gaze point of the user is within a predetermined distance from apredetermined area; determining that a gaze point of the user is movingtowards a predetermined area; determining that a gaze point of the useris fixed at a predetermined area for a predetermined amount of time;detecting a gesture; detecting a sound; and receiving a command from amanual input device. The predetermined area may for example be theviewing area of the display. The manual input device may for example bea button, a knob or a stick.

The method may comprise, before the sending step, a step of visuallyindicating the selected further element. The purpose of the visuallyindicating step is to inform the user of which further element he or shehas selected. Thereby, the risk that a function other than the oneintended by the user is performed is reduced.

The visually indicating step may for example comprise highlighting theselected further element. Highlighting the selected further element mayfor example include at least one of: changing the colour, shape or sizeof the selected further element; making the selected further elementbrighter or darker; making the selected further element fade; andremoving the non-selected further elements from the display. Further,the visually indicating step may comprise replacing the selected furtherelement with one or more different graphical user interface element. Forexample, the selected further element may be replaced by a graphicaluser element representing a menu allowing the user to choose betweendifferent options. Still further, the visually indicating step maycomprise moving the selected further element on the display. In suchcase, the selected further element may move on the screen while theoperation of the machine changes in some way, the movement of theselected further element thereby being a visual representation of thechange in operation. For example, the selected further element may moveon the screen while the volume of a car radio or the temperature insidea car is being adjusted.

The method may comprise, before the sending step, a step of receiving aconfirmation from the user to perform the at least one of the one ormore functions associated with the selected further element. The purposeof the receiving step is to allow the user to send a confirmation thatthe selected function is the one he or she intended to select. Thereby,the risk that a function other than the one intended by the user isperformed is reduced. The receiving step may comprise at least one ofthe steps: determining that the gaze of the user is fixed at the secondgaze point for a predetermined amount of time; detecting an eye blink ofthe user; detecting a gesture; detecting a sound; and receiving acommand from a manual input device.

The method may comprise calibrating an eye tracker based on the positionof the initial element and the first gaze point. The position of thefirst gaze point and the position of the initial element may bedifferent, and the position information can be used to calibrate an eyetracker so as to increase its accuracy.

According to a second aspect of the invention, there is presented asystem for visual interaction between a user and a machine using gazeestimation, comprising: a graphics module configured to display aninitial element and at least one further element on a display, theinitial element having a fixed position, each further element beingassociated with one or more functions of the machine and having a fixedposition spatially separated from the position of the initial element,whereby each further element defines an angular range with respect tothe position of the initial element; an eye tracker configured toestimate a first gaze point and a second gaze point of the user; andprocessing circuitry connected to the graphics module and the eyetracker, the processing circuitry being configured to determine that adirection from the first gaze point to the second gaze point lies withinthe angular range defined by a selected further element of the one ormore further elements, and send a signal instructing the machine toperform at least one of the one or more functions associated with theselected element.

The effects and features of the second aspect of the invention aresubstantially analogous to those of the first aspect of the inventiondescribed above.

The graphics module may be configured to visually indicate the selectedfurther element to the user. For example, the graphics module may beconfigured to highlight the selected further element. As anotherexample, the graphics module may be configured to move the selectedfurther element on the display.

The processing circuitry may be configured to receive a confirmationfrom the user to perform the at least one of the one or more functionsassociated with the selected further element.

The eye tracker may be configured for calibration based on the positionof the initial element and the first gaze point.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in more detail with reference to theappended drawings, in which:

FIG. 1 shows a schematic view of a system for visual interaction betweena user and a machine using gaze estimation according to an embodiment ofthe invention;

FIGS. 2a, 2b, 2c, 2d and 2e show schematic views of a part of the systemin FIG. 1 during use thereof;

FIG. 3 shows a flowchart of a method for visual interaction between auser and a machine using gaze estimation according to an embodiment ofthe invention; and

FIG. 4 shows schematically an interior view of a vehicle equipped with asystem for visual interaction between a user and a machine using gazeestimation according to an embodiment of the invention.

Like reference numerals refer to like elements throughout.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

FIG. 1 shows a perspective view of a system 1 for visual interactionbetween a user 10, schematically represented by an eye, and a machine 20using gaze estimation. The user 10 may select a function of the machine20 via the display 30 using his or her gaze. The display 30 is here aflat panel display, specifically one using light-emitting diodes, butthe system 1 may be used with other types of displays. The machine 20may for example be a piece of equipment integrated with a vehicle.Examples of such pieces of equipment include car radios and car climatecontrol systems. In such case, the function of the machine 20 may forexample be to change the radio frequency or to switch the heat on oroff. As another example, the machine 20 may be a computer, such as adesktop computer or a tablet computer. In such case, the function of themachine 20 may for example be to execute a piece of software stored onthe computer or to type letters using a virtual keyboard shown on thedisplay 30. As yet another example, the machine 20 may be a device in acomputer network and may be configured to execute procedures remotely onother devices in the network, for example via a Remote Procedure Call.Hence, it should be clear that the terms “machine” and “function”, asused herein, are meant to be interpreted broadly.

As illustrated in FIG. 1, the system 1 comprises a graphics module 2configured to display a graphical user interface on the display 30. Theconnection between the graphics module 1 and the display 30 is in thiscase a wired connection, but may be a wireless connection in a differentexample.

The system 1 further comprises an eye tracker 3. The eye tracker 3 is inthis case of a conventional type and located below the display 30.However, the eye tracker 3 may have a different position in a differentexample. The eye tracker 3 is configured to estimate where the user 10is gazing.

The system 1 comprises processing circuitry 4 connected to the graphicsmodule 2, the eye tracker 3 and the machine 20. The processing circuitry4 is in this case connected to these components via wired connections.However, it is conceivable to use wireless connections instead of wiredconnections. The processing circuitry 4 is configured to control thegraphics module 2 and to receive data regarding the position of the gaze11 of the user 10 from the eye tracker 2. Further, when the user 10moves his or her gaze 11, the processing circuitry 4 is here configuredto use the position information to determine the direction in which thegaze 11 moves. The processing circuitry 4 is also configured to sendinstructions to the machine 20.

It is noted that, even though the graphics module 2, the eye tracker 3and the processing circuitry 4 are illustrated as separate components inFIG. 1, this may or may not be the case in a different example. Forexample, the graphics module 2 may be integrated with the processingcircuitry 4. As another example, the graphics module 2 and theprocessing circuitry 4 may be integrated with the eye tracker 3. Thus,some, or all, of these components may form part of a single unit in adifferent example.

In use, the system 1 operates as described in the following withreference to FIGS. 2a, 2b, 2c, 2d, 2e and 3, and with continuedreference to FIG. 1. FIG. 2a shows a front view of the display 30 at anearlier point in time than FIGS. 2b, 2c, 2d and 2e , which showperspective views of the display 30.

In a step S1, an interaction mode of the system 1 is activated. The user10 can interact visually with the system 1 when the interaction mode isactivated. In this case the system 1 enters the interaction mode whenthe eye tracker 3 estimates that the user's 11 gaze is located at apredetermined distance d from the display 30 (see FIG. 2a ). Thus, theinteraction mode is here automatically activated. It is noted that thereare other ways in which the interaction mode can be activated. Forexample, the system 1 may be configured to enter the interaction modewhen the gaze 11 of the user 10 is estimated to be moving towards thedisplay 30 or to be located at, or moving towards, a predetermineddistance from an area or a point on the display 30. Further, the system1 may be configured such that the user 10 can activate the interactionmode manually, for example by making a sound or a gesture.Alternatively, or in addition, the system 1 may include a manual inputdevice allowing the user 10 to send a command to the system 1 so thatthe system 1 switches to the interaction mode. Such a manual inputdevice may for example be a knob or button on a computer mouse or on acontrol panel inside a car.

The system 1 may be configured such that the system 1 leaves theinteraction mode when the user 10 moves the gaze 11 away from thedisplay 30. In such case, the user 10 may cancel the selection processat any time by moving the gaze away from the display 30. The system 1may be adapted to, for example, turn the display 30 dark if the user 10cancels the selection process. In a step S2, after the interaction modehas been activated, the graphics module 2 displays an initial element 31on the display 30 (see FIG. 2a ). The initial element 31 is here agraphical user interface element. The initial element 31 has a fixedposition on the display 30, so the initial element 31 does not move onthe display 30. In this case, the initial element 31 has a circularshape and is located at the centre of the display 30. Of course, theinitial element 31 can in general have any position and shape deemedsuitable.

In a step S3, the eye tracker 3 estimates a first gaze point 12 of theuser 10 (see FIG. 2b ). The eye tracker 3 generally tracks the gaze 11of the user 10 continuously, and may estimate the first gaze point 12 asa point of gaze which is constant for more than a required period oftime, indicating that the user 10 has rested his/her gaze on the initialelement 31. The processing circuitry 4 may wait a predetermined amountof time after the initial element 31 is first shown on the display 30for the eye tracker 3 to provide the first gaze point 12. If no gazepoint is obtained within the predetermined time (i.e. the eye tracker 3cannot determine that the user 10 has focused his/her gaze), or if theprocessing circuitry 4 receives a gaze point which is not in thevicinity of the initial element 31, the processing circuitry 4 mayinstruct the graphics module 2 to remove the initial element from thedisplay 30, and processing returns to step S1.

Depending on the calibration of the eye tracker 3, the estimated firstgaze point 12 may or may not correspond to the location of the initialelement 31. As can be seen in FIG. 2b , the first gaze point 12 is inthis case not located on the initial element 31. In other words, theuser 10 is looking at the initial element 31, but the estimated gazepoint is slightly offset due to imperfect calibration of the eye tracker3.

It is noted that the eye tracker 3 may be adapted to estimate the firstgaze point 12 by first estimating two gaze points, one for each eye ofthe user 10, and then determining the first gaze point 12 based on thosetwo gaze points, for example by taking an average thereof. This way ofdetermining the gaze of the user 10 makes the system 1 relatively robustagainst, for example, events that might cause the eye tracker 3 totemporarily lose track of one of the eyes of the user 10, such as eyeblinks.

In a step S4, the processing circuitry 4 assumes that the user 10 isgazing at the initial element 31. The processing circuitry 4 typicallymakes this assumption immediately after the first gaze point 12 has beenestimated, so that there is no time for the user 10 to move his or hergaze 11.

In a step S5, which is subsequent to the step S4 described above, thegraphics module 2 displays one or more further elements 32 a, 32 b, 32c, 32 d on the display 30 (see FIG. 2b ). In this case there are fourfurther elements 32 a, 32 b, 32 c, 32 d displayed on the display 30, butin general the number of further elements 32 a, 32 b, 32 c, 32 d may begreater or smaller than four. Each one of the further elements 32 a, 32b, 32 c, 32 d is a graphical user interface element and associated witha function of the machine 20. The further elements 32 a, 32 b, 32 c, 32d have respective fixed positions on the display 30. Thus, the furtherelements 32 a, 32 b, 32 c, 32 d do not move on the display 30. Thepositions of the further elements 32 a, 32 b, 32 c, 32 d are spatiallyseparated from the position of the initial element 31. In theillustrated example, the four further elements 32 a, 32 b, 32 c, 32 dare located generally above, below, to the right of, and to the left of,respectively, the initial element 31. The further element 32 a, 32 b, 32c, 32 d may of course have other locations relative to the initialelement 31 in a different example. The initial element 31 here does notoverlap with any of the further elements 32 a, 32 b, 32 c, 32 d, butthis may or may not be the case in a different example. The furtherelements 32 a, 32 b, 32 c, 32 d are in this case wedge-shaped andarranged so as to form a pie menu. However, the further elements 32 a,32 b, 32 c, 32 d are not limited to any particular shape orconfiguration. Thus, the further elements 32 a, 32 b, 32 c, 32 d can forexample be circular or rectangular, and do not have to form a pie menu.

The further elements 32 a, 32 b, 32 c, 32 d define respective angularranges α_(a), α_(b), α_(c), α_(d) relative to the initial element 31. Asis illustrated in FIG. 2b , the angular range α_(a), for example, may inthis case be seen as corresponding to a sector of a circle, the circlebeing centred on the initial element 31 and the sector covering thefurther element 32 a. In this case the angular ranges α_(a), α_(b),α_(c), α_(d) add up to a full circle, although this may or may not bethe case in a different example.

As can also be seen in FIG. 2b , each of the angular ranges α_(a),α_(b), α_(c), α_(d) corresponds in this case to a quarter of a circle.Stated differently, each of the angular ranges α_(a), α_(b), α_(c),α_(d) has a “width” of 90°. However, in a different example, the angularranges may have a different width, and all of the angular ranges do nothave to have the same width. In general, the widths of the angularranges depend on, for example, the number of further elements, the sizesof the further elements and the positions of the further elements on thedisplay.

In a step S6, the eye tracker 3 estimates that the gaze 11 is directedat a second gaze point 13 (see FIG. 2c ). Specifically, the user 10 mayselect one of the further elements 32 a, 32 b, 32 c, 32 d by moving thegaze 11. In the example illustrated in FIG. 2c , the user 10 moves thegaze 11 to the right in order to select the further element 32 b that islocated to the right of the initial element 31. Upon detecting that thegaze 11 of the user 10 has moved, the eye tracker 3 estimates that thegaze 11 is directed at the second gaze point 13. In general, the secondgaze point 13 may or may not be located on the further element the user10 intends to select. As can be seen in FIG. 2c , the second gaze point13 is in this case not located on the further element 32 b located tothe right of the initial element 31. It is noted that the eye tracker 3may be adapted to utilize the gazes of both eyes of the user 10 whenestimating the second gaze point 13 (see also the discussion above inconnection with step S3).

In a step S7, the processing circuitry 4 determines the direction D thatgoes from the first gaze point 12 to the second gaze point 13. Thedirection D is in this case straight to the right. The direction D maybe determined in several different ways. The direction D may for examplebe determined by finding the direction angle of the vector going fromthe first gaze point 12 to the second gaze point 13. As another example,the direction D may be determined by finding the vector going from thefirst gaze point 12 to the second gaze point 13, which includesdetermining the direction angle and the length of the vector.

The processing circuitry 4 compares the determined direction D with theangular ranges α_(a), α_(b), α_(c), α_(d) defined by the furtherelements 32 a, 32 b, 32 c, 32 d. In this case, the determined directionD lies within the angular range α_(b) defined by the further element 32b, and, accordingly, the processing circuitry 4 determines that the user10 has selected the further element 32 b. Thus, the choice of the user10 is determined by a relative gaze movement rather than an absolutegaze direction.

It is noted that the processing circuitry 4 determines that the furtherelement 32 b, say, has been selected as long as the direction D iswithin the angular range α_(b). So, in this case, the user 10 does nothave to move the gaze 11 straight to the right in order to select thefurther element 32 b, but could move the gaze 11 in a direction pointingrightward and slightly upward or downward.

Further, it is noted that there may, in a different example, bedirections which do not correspond to a further element because, forexample, the angular ranges defined by the further elements do not addup to a full circle. In such case, if the direction D is determined notto lie within one of the angular ranges, the system 1 may for example beadapted to simply wait for the user 10 to move the gaze 11 again and/orsignal to the user 10 that he or she needs to move the gaze 11 again tomake a selection. In an optional step S8, the graphics module 2 visuallyindicates the further element 32 b to the right (see FIGS. 2c, 2d and 2e). Thereby, the user 10 sees which further element he or she hasselected. In this case, the processing circuitry 4 instructs thegraphics module 3 which one of the further elements 32 a, 32 b, 32 c, 32d to visually indicate. There are several ways in which the graphicsmodule 2 can visually indicate which one of the further elements 32 a,32 b, 32 c, 32 d the user 10 has selected. The selected further elementmay for example light up (see FIG. 2c ). As another example, thegraphics module 2 can visually indicate the selected further element byreplacing the selected further element with another graphical userelement representing a menu which presents new options to the user 10(see FIG. 2d ). Thus, the graphics module 2 may be adapted to presenthierarchical menus to the user 10. Using hierarchical menus is one wayof associating a further element with several functions of the machine20. Further, the graphics module 2 can visually indicate the selectedfurther element by, for example, moving the selected further element onthe display 30 (see FIG. 2e ), spinning the selected further elementand/or making the selected further element pulsate.

It is noted that the system 1 may be configured to indicate to the user10 which further element 32 a, 32 b, 32 c, 32 d he or she has selectedin a non-visual manner. For example, the system 1 may be capable ofgiving an audio indication, such as a voice message or a sound signal,via a speaker.

In an optional step S9, the system 1 here receives a confirmation fromthe user 10 that the visually indicated further element 32 b is the onethe user 10 intended to select. Several alternatives exist for allowingthe user 10 to confirm his or her selection. The system 1 may forexample be configured such that the user 10 can confirm the selection byat least one of: blinking an eye; making a gesture; making a sound; andfixing the gaze 11 at the second gaze point 13, or an area around thesecond gaze point 13, for a predetermined amount of time. Alternatively,or in addition, the system 1 may be configured such that the user mayconfirm the selection by sending a command to the system 1 using amanual input device, such as a button, a knob or a stick.

It is noted that the system 1 may be configured such that the user 10can “de-select” a further element which has been visually indicated butwhich is not the one the user 10 intended to select. For example, theuser 10 may be able to de-select a visually indicated further element bymoving the gaze 11 away from the second gaze point 13. Alternatively, orin addition, the system 1 may be configured such that the user mayde-select a visually indicated further element by sending a command tothe system 1 using a manual input device, such as a button, a knob or astick.

In a step S10, after having received the confirmation from the user 10,the processing circuitry 4 sends a signal instructing the machine 20 toperform the function associated with the selected further element 32 b.The machine 20 then performs the function that the user 10 has selected.

In an optional step S11, the eye tracker 3 is here calibrated based onthe position of the initial element 31 and the estimated first gazepoint 12. For example, the eye tracker 3 may auto-calibrate, i.e. theeye tracker 3 may calibrate itself. It is noted that the calibratingstep S11 may occur any time after the estimation of the second gazepoint 13 in step S6.

Turning now to FIG. 4, there is shown an interior view of a vehicle 40equipped with a system 1 for human-machine interaction using gazeestimation. The system 1 in FIG. 4 is similar to the system describedabove with respect to FIGS. 1 to 3. The vehicle 40 is in this case acar, although the system 1 may be integrated in other road vehicles,such as trucks, and also in aircrafts and watercrafts, such as airplanesand boats. The car 40 has three displays 30′, 30″, 30′″ which areconnected to the system 1. Each display 30′, 30″, 30′″ is associatedwith one or more machines integrated with the car, such as an audiosystem, a climate control system, etc. A driver of the car 40 can usehis or her gaze to control the machines. In use, the system 1 typicallycontinuously monitors the gaze of the driver using an eye tracker 3.When detecting that the gaze of the driver is directed near one of thedisplays 30′, 30″, 30′″ for more than a predetermined amount time, thesystem 1 enters the interaction mode and shows an initial element onthat particular display. The driver may then select a function of themachine(s) associated with that particular display in the mannerdescribed above with respect to FIGS. 1 to 3.

The person skilled in the art realizes that the present invention by nomeans is limited to the preferred embodiments described above. On thecontrary, many modifications and variations are possible within thescope of the appended claims. For example, some of the steps S1 to S10can be performed simultaneously, such as the visually indicating step S8and the sending step S10.

In the claims, any reference signs placed between parentheses shall notbe construed as limiting to the claim. The word “comprising” does notexclude the presence of other elements or steps than those listed in theclaim. The word “a” or “an” preceding an element does not exclude thepresence of a plurality of such elements.

1-14. (canceled)
 15. A method for visual interaction between a user anda machine using gaze estimation, wherein the method comprises activatingan interaction mode, and wherein the interaction mode comprises thesteps of: displaying an initial element on a display, the initialelement having a fixed position; estimating a first gaze point of theuser; assuming that the user is gazing at the initial element;displaying one or more further elements on the display, each furtherelement being associated with one or more functions of the machine andhaving a fixed position spatially separated from the position of theinitial element, whereby each further element defines an angular rangewith respect to the position of the initial element; estimating a secondgaze point of the user; determining that a direction from the first gazepoint to the second gaze point lies within the angular range defined bya selected further element of said one or more further elements; andsending instructions to the machine to perform at least one of the oneor more functions associated with the selected element.
 16. The methodaccording to claim 15, wherein the activating step comprises at leastone of the steps: determining that a gaze point of the user is within apredetermined distance from a predetermined area; determining that agaze point of the user is moving towards a predetermined area;determining that a gaze point of the user is fixed at a predeterminedarea for a predetermined amount of time; detecting a gesture; detectinga sound; and receiving a command from a manual input device.
 17. Themethod according to claim 15, comprising, before the sending step, astep of visually indicating the selected further element.
 18. The methodaccording to claim 17, wherein the visually indicating step compriseshighlighting the selected further element.
 19. The method according toclaim 17, wherein the visually indicating step comprises moving theselected further element on the display.
 20. The method according toclaim 15, comprising, before the sending step, a step of receiving aconfirmation from the user to perform said at least one of the one ormore functions associated with the selected further element.
 21. Themethod according to claim 20, wherein the receiving step comprises atleast one of the steps: determining that the gaze of the user is fixedat the second gaze point for a predetermined amount of time; detectingan eye blink of the user; detecting a gesture; detecting a sound; andreceiving a command from a manual input device.
 22. The method accordingto claim 15, comprising calibrating an eye tracker based on the positionof the initial element and the first gaze point.
 23. A system for visualinteraction between a user and a machine using gaze estimation,comprising: a graphics module configured to display an initial elementand at least one further element on a display, the initial elementhaving a fixed position, each further element being associated with oneor more functions of the machine and having a fixed position spatiallyseparated from the position of the initial element, whereby each furtherelement defines an angular range with respect to the position of theinitial element; an eye tracker configured to estimate a first gazepoint and a second gaze point of the user; and processing circuitryconnected to the graphics module and the eye tracker, the processingcircuitry being configured to determine that a direction from the firstgaze point to the second gaze point lies within the angular rangedefined by a selected further element of said one or more furtherelements, and send a signal instructing the machine to perform at leastone of the one or more functions associated with the selected element.24. The system according to claim 23, wherein the graphics module isconfigured to visually indicate the selected further element to theuser.
 25. The system according to claim 23, wherein the graphics moduleis configured to highlight the selected further element.
 26. The systemaccording to claim 23, wherein the graphics module is configured to movethe selected further element on the display.
 27. The system according toclaim 23, wherein the processing circuitry is configured to receive aconfirmation from the user to perform said at least one of the one ormore functions associated with the selected further element.
 28. Thesystem according to claim 23 wherein the eye tracker is configured forcalibration based on the position of the initial element and the firstgaze point.